Fig. 4
Wingless queens from the Northern and the Southern Sky Islands show different growth patterns. a Surface area (μm2) of leg discs (x-axis) versus vestigial wing disc (y-axis) for wingless queen last instar larvae from different mountain ranges. A line was fitted through with a Standardized Major Axis bivariate line-fitting analysis. The slopes are significantly different from each other (p-value = 0.00017), reflecting an evolutionary change affecting developmental trajectories of imaginal discs among different mountains since their isolation. b Winged queen larvae shows extensive cell division in imaginal discs in last larval instar. Wingless queen larvae from the Northern Sky Islands c Pinals and the d Catalinas show very few cell divisions in their vestigial wing discs while the Southern Sky Islands, the e Huachucas and f Chiricahuas show more. Red is PH3, green is DAPI, and yellow arrowheads indicate a cell that is expressing PH3. g Map of the Sky Islands indicating the position of Northern and Southern Sky Islands. h Graph of the number of dividing cells per unit area in vestigial discs of wingless queen larva from different Sky Islands. The x-axis shows the different mountain ranges and the y-axis the number of cells dividing per (μm2). The number of dividing cells per unit area in vestigial wing discs differs between Northern and Southern Sky Islands (ANOVA, p <0.0001). Thus, the vestigial wing discs of queens from Southern Sky Islands show significantly higher levels of cell division and are larger than vestigial wing discs of queens from Northern Sky Islands